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Bộ đề dự đoán kì thi THPT Quốc Gia năm 2019 chuẩn (Kèm lời giải) môn Toán

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Khối đa diện chứa đỉnh A có V V<br />

'.<br />

V<br />

'.<br />

.<br />

A C AEFC C ANE<br />

S<br />

AEFC<br />

7 7 1 7<br />

Ta có VC '. AEFC<br />

. VC '. ABC<br />

VC '. ABC<br />

. V V.<br />

S<br />

8 8 3 24<br />

ABC<br />

Ta có<br />

CA 2 1 1 1 1<br />

CM IA AN IA AN CC ' AA'.<br />

CI CF 3 IC 3 CC ' IC 3 3 3<br />

Do đó<br />

1<br />

1 1 1<br />

.<br />

. AA'.<br />

AB<br />

S<br />

AN AE<br />

ANE<br />

2 2 2 3 2 2 1<br />

VC '. ANE<br />

. VC ', ABB' A'<br />

. V . V V.<br />

S AA'. AB 3 AA'. AB 3 18<br />

ABB'<br />

A'<br />

7 1 25<br />

Vậy V <br />

A<br />

V V .<br />

24 18 72<br />

Chọn đáp án B.<br />

NGUYEN THANH TU PRODUCTION<br />

21

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